Pinning Effect on Fermi Level in 4H-SiC Schottky Diode Caused by 40-MeV Si Ions

Abstract

The changes in the electrical properties of 4H-SiC Schottky diodes caused by 40-MeV Si ions with different fluences are investigated. The irradiation fluences are selected as $1.0 \times 10^{9}$ , $8.9\times 10^{9}$ , and $1.5 \times 10^{10}$ cm−2, respectively. The diodes were characterized using deep-level transient spectroscopy (DLTS) and Keithley 4200-SCS semiconductor characterization system. The TRIM software is used to estimate the carbon distribution of vacancies in the irradiated 4H-SiC diodes by 40-MeV Si ions. As irradiation fluence increases, the ideality factors increase from 1.01 to 1.09, while the Schottky barrier height decreases from 1.16 to 1.09 eV. The free-carrier concentration $N_{d}$ decreases with the increasing fluence from $1.0 \times 10^{9}$ to $1.5 \times 10^{10}$ cm−2. The free-carrier removal rate is estimated to be $2.4 \times 10^{6}$ cm−1. Experimental and simulated results show that 40-MeV Si ions produce high concentrations of displacement defects ( $Z_{1}/Z_{2}$ center) in the 4H-SiC, leading to the Fermi level to be pinned at the deep levels.